As more and more individuals are utilizing electronic mail as a tool for communication, unsolicited junk email has become a problem. To enable users to reduce the amount of junk email (“spam”) that they receive, many email filtering tools have been developed. One of the most effective email filters is an exclusive filter based on entries in a user's email address book. For example, an exclusive email filter identifies as junk mail, any email received from an email address not found in the recipients address book.
While this is an effective filtering technique, it is likely that many email messages may be identified as junk mail when, in fact, they are email that the recipient would like to receive. For example, if a user has the email address of a friend in their address book, emails from that friend will be received. However, if the friend passes on the user's email address to another friend, any emails received from that individual will be classified as junk mail until the user adds the new friend's email address to their address book.
Accordingly, a need exists for an email filter that classifies an email received from a friend of a friend as being a trusted email rather than a junk email.